If you replace DMR or NXDN instead of TETRA, this could be a post from the past prior to those digital modes being added. I also seem to recall just prior to MotoTRBO/DMR being added, some were saying "no way this is needed or going to happen". If you happen to be in an area where TETRA is being used, you might think otherwise. So far in Chicago, only 1 system exists at O'Hare Airport. Since I'm not close enough, I would apply an upgrade to my SDS100 only at this time and go there and update the talk groups in the database. So yes, the need is "starting" to be there, but not yet.
I'd like to see bug fixes take priority at this time, some of the nuisance ones corrected would be nice. But, if Sentinel was updated to allow TETRA systems to be added, firmware added to allow TETRA to be added, and a paid upgrade made available, the good news is you don't have to apply them if you don't want them. For me, Provoice has no use, but for those that need or want it, it's available and I'm sure they're happy.
Let's keep it on the radar, and if the technology is there to add it, I hope Uniden does so. I'm not sure why some are getting their panties in a bunch over this, when no one is forcing you to do anything. Relax everyone.